[Posttransplant complications: GVHD and SOS/VOD].

Several novel agents (e.g., molecularly targeted drug, bispecific antibody, antibody-drug conjugate, chimeric antigen receptor T-cell therapy) have successively emerged in clinical practice and are occasionally used in allogeneic hematopoietic cell transplantation (allo-HCT) settings. These drugs are expected to reduce pretransplant tumors, lower the risk of relapse with posttransplant maintenance therapy, and consequently improve transplant outcomes. Additionally, some molecularly targeted drugs could be adapted to treat steroid-refractory acute and/or chronic graft-versus-host disease (GVHD), which remained the leading cause of nonrelapse mortality after allo-HCT. However, these agents develop an excessive immune reaction, including GVHD, or presented an increased risk of sinusoidal obstruction syndrome (SOS)/veno-occlusive disease (VOD) as their "off-target" effects. Thus, this review aimed to summarize the risk assessment and management of post-posttransplant complications, focusing on GVHD and SOS/VOD, in the era of molecularly targeted therapy. Moreover, recent advances in GVHD or SOS/VOD prophylaxis and treatment using novel agents/devices are also discussed.